Sulfur recovery

ABSTRACT

Sulfur is continuously extracted from sulfur-bearing ore, found or brought to the surface, by injecting said ore through a tubular conduit containing a downstream sulfur extraction section. After sulfur is extracted, the residual trailings are further coursed upstream through a second tubular conduit to an exit point.

Unit

[72] Inventor RuelCarltonTerry 1,317,625 9/1919 Huff 23/308 Houston,Tex. 1,408,467 3/1922 Perrym. 1. 23/308 21 Appl. No. 802,817 1,457,793 6/1923 Perry 23/308 [22] Filed Feb. 27,1969 1,731,563 10/1929 Crowley 23/308 [45] Patented Oct. 26,1971 1,841,697 1/1932 Andrews 23/308 [73] Assignee Allied Chemical Corporation 1,990,602 2/1935 Guernsey 23/308 New York, NY. 2,088,190 7/1937 Du Pont 23/270 X 2,934,413 4/1960 McGauley 23/308 3,042,502 7/1962 McGauley 23/308 1 SULFUR RECOYERY 3,440,026 4/1969 Dubow 23/308 5 Claims, 1 Drawmg Fig. Primary Examiner Norman Yudkoff [52] US. Cl 1. 23/308 S, Assistant s Emery 23/312 S, 23/270 R, 215/2726 R, 23/229 A t jonathan plant [51] Int. Cl C011) 17/08 [50] Field of Search 23/267,

309, 229 ABSTRACT: Sulfur is continuously extracted from sulfurbearing ore, found or brought to the surface, by injecting said [56] References Cited ore through a tubular conduit containing a downstream sulfur UNITED STATES PATENTS extraction section. After sulfur is extracted, the residual 550,035 11/1895 Wheeler 23/270 X trailings are further coursed upstream through a second tubu- 889,120 5/1908 Gormly 23/270 lar conduit to an exit point TER GANGUE A I ow 3 wncn PLUS EXTRACTION zo- I UP a A SULFUR s SETEHAEMTED iL SULFUR I3 on: 17a

SULFUR RECOVERY BACKGROUND OF Til-IE INVENTION This invention relates to a continuous process for recovering sulfur from sulfur-bearing ore found at or brought to the surface. It is specially advantageous, but not limited, to mine sites located in mountainous regions. More particularly, sulfur is extracted from ore deposits, at or near the surface, by injecting said ore downwardly through a tubular conduit containing a downstream sulfur extraction section. After sulfur is extracted from the ore, the residual trailings are further coursed upwardly through a second tubular conduit to an exit point preferably contiguous with the mining site if used in such a location.

l-leretofore known methods of extracting sulfur contained in low-grade ores found at or near the surface, for example, in mountainous regions, have been expensive, wasteful and therefore of peripheral utility. Such methods could not, in general, compete effectively with subsurface extraction processes employing Frasch-type techniques. A further impractical feature of prior surface recovery techniques is the extent to which they rely on batch or semibatch processing methods.

The present invention provides for a continuous flow of preheated ore to and through an instream sulfur extraction section and with continuous deposit of residual trailings, in close proximity to the mine site where said trailings can be used for backfill. Other, and more distinct, advantages of the present process will become apparent upon examination of the following detailed disclosure.

SUMMARY OF THE INVENTION In accordance with the instant invention, crushed sulfurbearing ore is moved, by conventional means, to the lip of a downwardly projecting, tubular inlet conduit and flushed downwardly through said conduit with water. The water is injected into said conduit at velocities sufficient to carry the ore into a convoluted sulfur extraction section wherein the temperature exceeds the melting point of sulfur. Upwardly moving superheated water is injected into the sulfur extraction section to maintain the flow of ore fragments and water in the desired direction. Sulfur is extracted from the ore and deposited in the lower portions of the convolutions. The extracted sulfur is removed from the convoluted portions of the sulfur extraction section and residual ore fragments are removed upwardly through an upwardly projecting, tubular outlet conduit. More particularly, in the present invention, sulfur is extracted from surface, or near surface, ore deposits by a process which utilizes the physical properties of elemental sulfur. Solid sulfur undergoes transition to the molten state at temperatures above 245 F. and in such molten state exhibits a tendency to agglomerate or coalesce excluding substantially all impurities. When the transition state environment is created by a superheated water, it is found that the water serves as a lubricant, and flushes sulfur from the residual ore (commonly referred to as gangue).

Generally, in the present process, a coarse sulfunbearing ore is injected downwardly through a tubular conduit, comprising a barometric column, connected at the lower periphery to a lateral, convoluted tubular section, wherein sulfur is extracted, said convoluted section also being connected at its other end to the lower periphery of a second tubular conduit, comprising a barometric column, through which residual ore is coursed upwardly to a deposit site. The present invention is particularly suited, but not limited to processing ore extracted from mountainside mining sites. Ores suitable for processing include materials wherein sulfur is found in an uncombined form, such as volcanic, hydrothermal fumaroleand solfataric-bearing materials. Even ores containing a low sulfur content, such as about -10 percent by weight, may be advantageously processed.

MOre specifically, coarse ore stockpiled for sulfur recovery therefrom is moved continuously to the lip of the tubular conduit and continuously drawn through said conduit with hot water, preferably recycle water. The water is injected into the conduit at velocities sufficient to carry the ore fragments into the convoluted sulfur extraction section, wherein the temperature of the environment surrounding the ore fragments is above the melting point of sulfur. The molten sulfur, because of its tendency to agglomerate (as a result of the physical fact that it, like mercury, has an affinity for itself) tends to join together as it melts at the elevated temperature, which has been reached in the extraction section. Under the influence of gravity, the agglomerating molten sulfur passes downwardly through the diameter of the extraction section and collects in the convolutions therein. As a result of preferential wetting, and continuous injections of upwardly moving water entering the extraction section, the gangue, even though heavier than water, is entrained upwardly through the second conduit connected at its lower periphery to the sulfur extraction section. Sulfur is continuously tapped from the convoluted portions of the extraction section. It is found that up to percent of the sulfur is separated from the ore.

The processing unit used in the instant procedure is easily adaptable to differing mining situations. The unit comprises in combination two substantially coextensive tubular conduits, in spaced relationship, and a lateral conduit section containing therein a convolution at each end section; a conduit being demountably connected at its lower periphery to each end portion of the lateral conduit section. The axes of the ore inlet and outlet conduits usually form an angle of between 25 and 75, but not limited thereto, with a horizontal plane passing through the lateral conduit section. Preferably the apparatus is placed such that the ore inlet is situated adjacent to the mining site with the extraction section at some point below the site and the residual ore outlet is situated at a point adjacent the mining site. The unit may also be at a remote location where gangue may be used for other commercial purposes, such as providing roadbuilding materials.

This processing unit may be formed from one continuous length of piping material or alternatively, the unit may be constructed from sections of piping materials that are demountably connected. The diameter of the piping materials comprising the ore inlet and outlet may also differ from the diameter of the material forming the sulfur extraction site.

BRIEF DESCRIPTION OF THE DRAWING The drawing shows a schematic illustration of the process and a W-shaped apparatus for carrying out the invention. The invention will now be described in more detail with relation to the aforementioned drawing.

DESCRIPTION OF THE PREFERRED EMBODIMENTS In the drawing, ore-bearing sulfur l is shown at the extreme left awaiting processing for extraction of the sulfur deposited therein. Said ore has been mined at or near the surface, or in such a manner as to not allow for mining by the conventional Frasch process or its equivalent, such as an ore body insufficiently buried to create sufficient mine pressure or an ore body situated in an arid region where there is an insufficient water supply, although the ore body is deep enough to mine by the Frasch process. In the embodiment shown in FIG. 11, ore fragments are lifted by conventional conveyor 2 to water column 5. It may be desirable to increase the wettability of the gangue as compared to the sulfur contained therein by introducing an acid, not shown, and to simultaneously neutralize the acidity of the slurry to minimize corrosion by the addition of a base, not shown, such as lime, downstream of the acid addition.

In the illustrated embodiment, the pressure at the bottom of the column 5 is about 53 p.s.i.g. This pressure is induced by positioning the water columns such that they upstand about ft. from ground level as ore enters the water column. The slurry of hot water and ore fragments is moved through water column 5, as a result of the continuous force exerted by pumped incoming hot water, of about 200 F., through line 3, to sulfur extraction section 7. Movement of the water is sufficient to carry ore through and therefrom the sulfur extraction section to the port of exit of the gangue, to be discussed hereinafter. As the ore moves through water column 5 toward the extraction zone under increasing back pressure, sulfur begins to melt from the ore.

Preheated water is tapped from water column 5, through line 11, carried to boiler 12 and distributed therefrom as hot water and preferably superheated water or steam, into the extraction zone at one or more points near the inlet portion of said sulfur extraction section, such as for example points 8 and 9, causing continued melting of the sulfur deposited in the ore. Valves 4 and 13 regulate, respectively, the flow to boiler 12 and the distribution from said boiler to points 8 and 9. As a result of introducing hot water, and preferably superheated water, the temperature within melting zone 7 reaches about 240 to 320 F., and preferably 275 F., under the influence of the static pressure created by water columns 5 and 16.

At this temperature, substantially all of the sulfur deposited in the crushed-ore slurry becomes molten, and as a result of its affinity for itself, as previously discussed, tends to agglomerate or fuse. Molten sulfur sloughs off the chamber surface into convolutions or depositories a and 10b and is tapped therefrom. The water entrains the gangue and removes it from the extraction zone upwardly through water column 16.

Molten sulfur collected at the bottom of convolutions 10a and 10b passes through lines 17a and 17b, which are valved at 18, to a collection pan 22, for example, for further filtering thereof or storage.

The gangue entrained by the moving water is moved upwardly through water column 16, which is closed at its upper periphery, and is drawn off through line 14 by means of pump 15 to desanders and desilters (not shown) and is removed by suitable means to a place where it may be dumped or used as backfill at the mining site or as road-building material. The water separated from the residual ore can be recovered, preheated and injected into conduit 5 through line 3. Water, including makeup water, can also be introduced into the system for an additional source through conduit 5.

As a result of employing apparatus as described, the present sulfur extraction process has a high thermal efficiency. The static pressure condition created in the melting chamber by use of water columns 5 and 16 results in the high temperatures achieved in said chamber and allows a minimization of the amount of water to be used in the system since water can be recovered and reused. Furthermore, the process is continuous, without internal moving parts in the melting chamber, and provides for a high recovery of sulfur from the ore, as much as 99 percent of the sulfur deposited in the ore being extracted, and is particularly adaptable to low-grade sulfur ores. Since it is continuous process, relying on the physical principles utilized in the Frasch process for separation of the agglomerating sulfur from the ore, it is highly economical and efficient.

A particular advantage of the W-shaped embodiment in the drawing is the facility with which it permits extraction of sulfur from sulfur-bearing ore found on hillside mining sites. The oblique section of the W comprising the sulfur extraction section can rest at ground level while the arms of the W comprising the inlet and outlet conduits upstand to the hillside site.

As previously mentioned, the continuous autoclave herein employed to extract sulfur is extremely flexible in the sense that it can be readily modified to meet changing production needs. The lengths and diameters of the water columns and melting chamber can be varied to accommodate different sulfur-bearing materials and different extraction time periods.

While the present invention has been described in detail with respect to specific embodiments thereof, it is not intended that these embodiments circumscribe the invention except as it is limited by the claims.

I claim: 1. A process for extracting sulfur from sulfur-bearing ore comprising moving crushed sulfur-bearing ore to the lip of a downwardly projecting, tubular inlet conduit; flushing the ore downwardly through said conduit with water; injecting the water into the upper portion of said conduit at velocities sufficient to carry the ore in a single desired direction through said downwardly projecting conduit and into a sulfur extraction section comprising an upwardly inclined cylindrical conduit section having a lowest part, a horizontal cylindrical conduit section of substantial lengths and a downwardly inclined cylindrical conduit section having a lowest part, wherein the temperature is above the melting point of sulfur; injecting from an inlet line upwardly moving superheated water into said horizontal section to maintain the flow of ore fragments and water in said single desired direction; extracting molten sulfur from the ore and depositing said extracted molten sulfur in said lowest parts of said inclined conduits section; removing sulfur from the bottom of said lowest parts of each inclined section; and removing residual ore fragments and water upwardly through an upwardly projecting, tubular outlet conduit.

2. The process for extracting sulfur from sulfur-bearing ore as described in claim 1, including the steps of withdrawing ore-laden water from the outlet conduit, separating the water from the residual ore and pumping said water to the inlet conduit and flushing it therethrough.

3. The process as set forth in claim 1, wherein the upwardly moving superheated water is injected into the extraction section at a plurality of points in said horizontal conduit section.

4. The process for extracting sulfur from sulfur-bearing ore as described in claim 1, wherein said water injected into said conduit to flush ore downwardly through said conduit is preheated to about 200 F.

5. The process for extracting sulfur from sulfur-bearing ore as described in claim 4, wherein a temperature is maintained within said sulfur extraction section of between 240 and 320 F.

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2. The process for extracting sulfur from sulfur-bearing ore as described in claim 1, including the steps of withdrawing ore-laden water from the outlet conduit, separating the water from the residual ore and pumping said water to the inlet conduit and flushing it therethrough.
 3. The process as set forth in claim 1, wherein the upwardly moving superheated water is injected into the extraction section at a plurality of points in said horizontal conduit section.
 4. The process for extracting sulfur from sulfur-bearing ore as described in claim 1, wherein said water injected into said conduit to flush ore downwardly through said conduit is preheated to about 200* F.
 5. The process for extracting sulfur from sulfur-bearing ore as described in claim 4, wherein a temperature is maintained within said sulfur extraction section of between 240 and 320* F. 